Leonard: All right, here's the deal. Sheldon is gone so the tree decorating rules are out the window.
Penny: Which means we don't have to use his ridiculous ornament spacing template.
Leonard: And I'm happy to report its Kickstarter campaign is holding steady at $0.

Leonard: Penny, as a scientist, my job is to figure out why things happen. But I don't think I'll ever understand how someone like me could get to be with someone like you. You know maybe I don't need to understand it, I just need to be grateful. I love you, Penny.

Leonard: What would you be if you were attached to another object by an inclined plane, wrapped helically around an axis?
Sheldon: Screwed?
Leonard: There you go.

Leonard: My point is, while you're spending all this time on your own, building computers or practicing your cello, what you're really doing is becoming interesting. When people finally do notice you, they're gonna find someone a lot cooler than they thought. And for those of you that were popular in high school, it's over, sorry. Thank you. Congratulations.

Raj: [to Amy] If you were having Sheldon's baby, would you really want him in the room?
Penny: Yeah, if he's in the room when they're making the baby, I'll give you $10.

Howard: I've never done this before, it's kinda fun.
Raj: Yeah, if your mom could see her little Bar Mitzvah boy, she'd have a heart attack.
Bernadette: Good idea. I'll take a picture.

Amy: Did you hold the baby?
Sheldon: I did.
Amy: And how did it make you feel?
Sheldon: Looking into the blank, innocent eyes of a creature that couldn't begin to comprehend anything I was saying ... basically another day at the office.